The present invention relates to an improved system for setting the ignition spark timing or "spark advance" on internal combustion engines using spark ignition.
By far the large majority of personal automobiles and small trucks in use today are powered by internal combustion gasoline engines wherein electrical discharge from a "spark plug" is used to ignite the compressed fuel-air mixture in each cylinder of the engine at a precise time during the engine cycle of operation.
Operation of internal combustion engines of the type referred to above is so well known that detailed description thereof is believed unnecessary. Suffice it to say that the ignition system of such an engine obviously includes a spark generator and distributor system having rotary components geared to the crankshaft of the engine. By such a system the electrical ignition pulses are generated and fed to the spark plug of each cylinder of the engine at an appropriate time to produce the series of sequential explosions in the cylinders needed to produce engine rotational operation.
In modern engines it is common practice to cause the ignition spark to be produced in each cylinder just slightly before the piston in that cylinder reaches its topmost or "top-dead center" position of its firing cycle. In addition, it is common practice to provide for an automatic spark advance, i.e., ignition slightly earlier in the cycle when it is required to produce increased power for acceleration, for example.
Setting or resetting the ignition timing for multi-cylinder gasoline engines in professional repair shops is often accomplished using sophisticated and expensive electronic computer equipment. However, such equipment is ordinarily unavailable to most of the vast number of amateur "handy man" types of automobile mechanics who out of preference or necessity perform repair work on their own or friends' car engines.
Even relatively inexpensive ignition timing equipment such as strobe light apparatus may be perceived as too costly for "do-it-yourselfers" who only occasionally have need of it. Further, such use of such timing apparatus requires that the engine be running. This may be a difficult condition to achieve for the amateur who has dismantled the engine beyond his ability to properly reassemble it for even marginal operation. Further, it has sometimes been found the timing indicator marks on the engine parts such as the front crankshaft hub or pulley are mis-positioned so that any strobe light timing setting would be inherently incorrect.
Thus, the present invention provides inexpensive easily operable apparatus useful to automobile engine mechanics and especially to do-it-yourself home mechanics for setting or resetting the electrical timing of an internal combustion engine while the engine is not running.